EP 0482776 A (CMB FOODCAN PLC.) 29.04.1992 describes prior art in which detachable pull ring can ends had a printed underside and were used for gaming purposes in America. However, over time, detachable pull ring ends were banned due to litter and environmental concerns.
U.S. Pat. No. 4,363,179 A (CROWN CORK & SEAL COMPANY, INC.) 14.12.1982 describes a beverage can end with retained-tab having concealed promotional material printed beneath the tab. This document describes how promotional material is printed on the surface of the can end under the tab around the rivet holding the tab to the can end. According to this document, it is impossible to view the promotional material without opening the can. However, the location and size of this printed, promotional material may result in it being difficult to read by a user of the beverage can.
EP 0482776 A (CMB FOODCAN PLC.) 29.04.1992 describes an alternative arrangement, in which the ring pull has an aperture adapted to retain a token. This document describes how the token may be removed by a user of the can to either act as proof of purchase or to qualify the user for a prize or other premium offer. However, the “token” described in this document may be considered to give rise to similar litter and environmental concerns as those raised previously with regard to detachable ring pulls.
Finally, EP 1218248 B (JOSEPH STASIUK) 03.02.2002 describes laser-etched pull-tabs and a methods for making the same. Laser-etching is described as an effective and cost efficient means of providing container opening devices having high definition and permanent indicia for promotional and other purposes.
As shown above, several beverage can ends are described in the prior art in which the tab used for opening the end or its location on the can end is marked in some way and provides an opportunity for promotional activities, for example awarding prizes and the like.